On Sun, 30 Oct 2011 06:38:30 -0400, Max Wolter <awishform...@gmail.com>
wrote:
Hello there.
I seem to be having problems wrapping my head around how to use the
ranges in the context of containers in phobos. Specifically, I can't
seem to figure out how to remove an element from a linked list.
foreach(cell; organism)
{
if(cell.x == x && cell.y == y)
{
organism.stableLinearRemove(cell);
break;
}
}
mind.d(123): Error: function
std.container.SList!(Cell).SList.linearRemove (Range r) is not callable
using argument types (Cell)
mind.d(123): Error: cannot implicitly convert expression (cell) of type
cell.Cell to Take!(Range)
I somehow get the feeling such a basic operation should just...work?
I offer an alternative collection library to std.container which has a
simpler (IMO) interface and features.
There is specifically a feature for removal during iteration. It would
look like this:
foreach(ref doRemove, cell; &organism.purge)
{
doRemove = cell.x == x && cell.y == y; // flag indicating the current
element should be removed
// note, not necessary to break here
if(doRemove)
break;
}
Note two things, removal during iteration is directly supported, meaning
it does not derail the iteration; and removal during iteration is a quick
operation (O(lg(n)) or better) in terms of the individual removal.
If you have a linked list, you can also do it the "range" way:
organism.remove(find!((a){return a.x == x && a.y ==
y;})(organism[]).begin);
begin is an accessor for a dcollections range that returns a reference
(cursor) to the first element in the range.
Note also that dcollections' linked list is doubly-linked, so removal is
O(1).
-Steve
